It's not a bad idea (unless there are extenuating circumstances) to spend as much time explaining to parents and guardians the reality of situations like this.
The mother seemed confused and upset that you were short. After you hang up a few minutes pass when your sergeant calls you. He wants to understand the reason behind your lack of decorum. He tells you to fix your bedside manner and put time and effort into explanations for these types of situations.
You call Z’s mother back and apologize. You explain the data associated with self-harm in the trans community. You talk about the increased probability of suicide within this community and that support is critical to maintain a healthy life. The conversation became very positive, and the mother seemed to understand.